Cezary Rzymkowski

Computerized Method for Work Space Optimization in Conditions of Static Work

The aim of this research was to develop a theoretical method for the ergonomic optimization of the work space of the upper limb. This method is based on a model of the upper extremity with 7 degrees of freedom. It consists of 3 rigid elements modeling the arm, forearm, and hand and 34 upper extremity muscles. The trunk is considered immobile. The shoulder joint is modeled as a rotating kinematics pair of third class, the elbow and wrist joints--of fourth class. The minimum sum of muscle force moments in the joints and soft saturation muscle cooperation criterion were used as merit criteria. The developed method makes it possible to effectively solve, in a defined work space, the task of work space optimization.

Assessment of perception of visual warning signals generated using an augmented reality system

One of the important measures to prevent industrial accidents consists in informing a machine operator about the appearance of hazardous situation quickly and effectively enough. The main aim of the paper is to present and discuss a methodology of proving - by means of the perception assessment - that the warning signals generated using the AR approach reveal the same effectiveness as standard visual signals coming from an industrial signalling device that is of common use in machinery. Twenty volunteers constituted a paid subject population for the study. In the course of experimental task execution the warning visual signals were generated using either a standard industrial signalling device or augmented reality glasses. Despite the fact that the experimental procedure has not been completed yet very promising primary results have been obtained has indicating that both the objective and subjective assessment indicators are better for the AR warning signals.

Structural dynamics of a girocopter: numerical approach in some emergency cases

Purpose This paper aims to present the assumptions, analysis and sample results of numerical modeling and analysis of dynamic events encountered in emergency cases during deployment of parachute rescue system (PRS) and hard landing of a small gyrocopter. The optimal design requires knowledge of structural loads and structural response – the information obtained often from experiment. Numerical simulation is presented as an alternative tool for estimating these data. Design/methodology/approach Structural analyses were performed using MSC.Nastran. Multibody simulations were done using MADYMO system. Findings Initial design parameters were evaluated and verified in numerical simulations. Some of the resulting conclusions were proven during the test flights. Practical implications Some chosen results of simulation of dynamic problems are presented. They can be useful as reference values for similar cases for light aircraft analysis. Originality/value The paper presents an alternative way of assessing structural response parameters in the case of emergency dynamic events of usage of PRS. The results can be used in other projects.

Analysis of the Possibilities of Improving the Safety of Children Transported in Passenger Cars in Pivoted Child Seat Systems

The study provides a comparative analysis of the possibility of mitigating the effects of head-on collisions on children transported in passenger cars in the safety seats fixed rotationally relative to the car cabin. The adopted testing method was computer simulation based on MADYMO system. The child was modeled as a “ellipsoid” dummy: Hybrid III 3-year-old Child Dummy fastened to the car safety seat with a five-point harness. The seat and the seat harness belts were modeled using finite element method (FEM). The simulation scenario corresponded to typical frontal collisions of cars with a rigid obstacle at the speed of approx. 50 km/h. To assess the degree of injury probability reduction in contrast to currently applied methods of car safety seats fastening – a synthetic injury probability index has been defined. The index is based on selected biomechanical injury criteria for chest, head and neck obtained as a result of simulations and standardized against literature data defining the values recognized as critical for 3-year-old children. The results prove considerable potential of reducing the risk of injury when using a rotating seat.

“Hybrid” Approach to Modelling of Biomechanical Systems

Two main methods of mathematical modelling of biomechanical systems: finite element method (FEM) and method of multi-body system analysis are compared in this paper. Main advantages and limitations of the both methods are pointed out. Then a compromise, task dedicated, “hybrid” solution is proposed. The model is implemented in the MADYMO software environment.